Re: [PATCH v9 04/13] nvmet: Allow ZNS target to support non-power_of_2 zone sizes

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 2022/08/03 2:47, Pankaj Raghav wrote:
> A generic bdev_zone_no() helper is added to calculate zone number for a
> given sector in a block device. This helper internally uses disk_zone_no()
> to find the zone number.
> 
> Use the helper bdev_zone_no() to calculate nr of zones. This let's us
> make modifications to the math if needed in one place and adds now
> support for zoned devices with non po2 zone size.
> 
> Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  drivers/nvme/target/zns.c | 3 +--
>  include/linux/blkdev.h    | 5 +++++
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
> index c7ef69f29fe4..662f1a92f39b 100644
> --- a/drivers/nvme/target/zns.c
> +++ b/drivers/nvme/target/zns.c
> @@ -241,8 +241,7 @@ static unsigned long nvmet_req_nr_zones_from_slba(struct nvmet_req *req)
>  {
>  	unsigned int sect = nvmet_lba_to_sect(req->ns, req->cmd->zmr.slba);
>  
> -	return bdev_nr_zones(req->ns->bdev) -
> -		(sect >> ilog2(bdev_zone_sectors(req->ns->bdev)));
> +	return bdev_nr_zones(req->ns->bdev) - bdev_zone_no(req->ns->bdev, sect);
>  }
>  
>  static unsigned long get_nr_zones_from_buf(struct nvmet_req *req, u32 bufsize)
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 5aa15172299d..ead848a15946 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1345,6 +1345,11 @@ static inline enum blk_zoned_model bdev_zoned_model(struct block_device *bdev)
>  	return BLK_ZONED_NONE;
>  }
>  
> +static inline unsigned int bdev_zone_no(struct block_device *bdev, sector_t sec)
> +{
> +	return disk_zone_no(bdev->bd_disk, sec);
> +}
> +
>  static inline int queue_dma_alignment(const struct request_queue *q)
>  {
>  	return q ? q->dma_alignment : 511;

I know that it is generally better to introduce a new helper together with its
user, but in this case, these 2 changes belong to different subsystems. So I
think it really may be better to have 2 patches here. Jens can decide about this
though.

-- 
Damien Le Moal
Western Digital Research